Everyone had a vision of the potential for intercomputer communication, but no one had ever sat down to construct protocols that could actually be used. It wasn’t BBN’s job to worry about that problem. The only promise anyone from BBN had made about the planned-for subnetwork of IMPs was that it would move packets back and forth, and make sure they got to their destination. It was entirely up to the host computer to figure out how to communicate with another host computer or what to do with the messages once it received them. This was called the “host-to-host” protocol.
